/**
 * ============================================================================
 *
 * Copyright (C) 2018, Hisilicon Technologies Co., Ltd. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1 Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *
 *   2 Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *
 *   3 Neither the names of the copyright holders nor the names of the
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * ============================================================================
 */

#ifndef THREAD_SAFE_QUEUE_H_
#define THREAD_SAFE_QUEUE_H_

#include <mutex>
#include <queue>

template<typename T>
class ThreadSafeQueue {
    public:

  /**
   * @brief ThreadSafeQueue constructor
   * @param [in] capacity: the queue capacity
   */
    ThreadSafeQueue(uint32_t capacity) {
    // check the input value: capacity is valid
        if (capacity >= kMinQueueCapacity && capacity <= kMaxQueueCapacity) {
            queueCapacity = capacity;
        } 
        else { // the input value: capacity is invalid, set the default value
            queueCapacity = kDefaultQueueCapacity;
        }
    }

  /**
   * @brief ThreadSafeQueue constructor
   */
    ThreadSafeQueue() {
        queueCapacity = kDefaultQueueCapacity;
    }

  /**
   * @brief ThreadSafeQueue destructor
   */
    ~ThreadSafeQueue() = default;

  /**
   * @brief push data to queue
   * @param [in] input_value: the value will push to the queue
   * @return true: success to push data; false: fail to push data
   */
    bool Push(T input_value) {
        std::lock_guard<std::mutex> lock(mutex_);

    // check current size is less than capacity
        if (queue_.size() < queueCapacity) {
            queue_.push(input_value);
            return true;
        }

        return false;
    }

  /**
   * @brief pop data from queue
   * @return true: success to pop data; false: fail to pop data
   */
    T Pop() {
        std::lock_guard<std::mutex> lock(mutex_);
        if (queue_.empty()) { // check the queue is empty
        return nullptr;
        }

        T tmp_ptr = queue_.front();
        queue_.pop();
        return tmp_ptr;
    }

  /**
   * @brief check the queue is empty
   * @return true: the queue is empty; false: the queue is not empty
   */
    bool empty() {
        std::lock_guard<std::mutex> lock(mutex_);
        return queue_.empty();
    }

  /**
   * @brief get the queue size
   * @return the queue size
   */
    int size() {
        std::lock_guard<std::mutex> lock(mutex_);
        return queue_.size();
    }

    private:
        std::queue<T> queue_; // the queue

        uint32_t queueCapacity; // queue capacity

        mutable std::mutex mutex_; // the mutex value

        const uint32_t kMinQueueCapacity = 1; // the minimum queue capacity

        const uint32_t kMaxQueueCapacity = 10000; // the maximum queue capacity

        const uint32_t kDefaultQueueCapacity = 10; // default queue capacity
};

#endif /* THREAD_SAFE_QUEUE_H_ */
